Means for removing non-condensible gases from boiler feedwater in a power plant



Oct. 6, 1964 J. F. SEBALD ETAL 3,151,461

MEANS FOR REMOVING NON-CONDENSIBLE GASES FROM BOILER FEEDWATER IN APOWER PLANT 2 Sheets-Sheet 1 Filed May 7, 1962 .oaon-aopuaooo I FIG.

JOSEPH FSEBALD IGOR J'. KARASSIK INVENTORS #AM,

Oct. 6, 1964 F. SEBALD ETAL 3,151,451

MEANS FOR REMOVING NON-CONDENSIBLE GASES FROM BOILER FEEDWATER m A POWERPLANT Filed may 7, 1962 2 Sheets-Sheet 2 FIG. 2

JOSEPH ESEBALD IGOR JTKARASSIK WW r United States Patent MEANS FURREMOVENG N QN-CQNDENSIELE GASES E i-RUM BUILER FEEDWATER IN A PGWERPLANT Joseph F. Sebald, Bloomfield, and Igor J. Kmassik, Maplewood, N1,assignors to Worthington orporation, Harrison, N.J., a corporation ofDelaware Filed May 7, 1962, Ser. No. 192,705 ill Llaims. {CL oil-67)This invention relates to power plants and more particularly to meansassociated with a surface condenser of the power plant acting to removethe non-condensible gases present in the boiler feedwater.

The need for the removal of air and other non-condensibie gases fromboiler feedwater has come about as a direct result of the progress thathas been made in boiler and turbine design in the last two or threedecades. Prior to that time boiler pressures and ratings werecomparatively low and there was, therefore, no need for elaborate watertreatment. When boiler pressures were stepped up and boiler ratingsincreased, it was found that boiler tubes failed more rapidly. Inaddition the formation of scale prevented the rapid transfer of heatfrom the tube to the water and increased the tube temperature causing itto fail.

The matter of proper removal of air and non-condensible gases has beenmentioned previously in the prior art and the approaches disclosed forproviding deaerated feedwater have served to reduce the problemsresulting from corrosion in the boiler of the power plant.

One such prior art arrangement disclosed provides means in a condensercoacting therewith to provide an arrangement for removingnon-condensible gases such as oxygen.

Specifically exhaust steam passed into the condenser was channeled toact against the condensate therein to provide the hi her degree ofdeaeration required in high pressure and temperature installations.

On startup of these prior art units a steam source was provided toreduce the partial air pressure in the condenser and to act to removenoncondensibles from the condensate.

It was found that these prior art arrangements were impractical incertain respects and especially during startup and failed to providecondensate of required purity for return to the boiler. Such a system isshown in US. Letters Patent 1,962,183.

More particularly this auxiliary steam source rather than effectivelyfunctioning to remove non-condensibles in a local area in the condensermerely blanketed the condenser in these areas and failed to achieve itsintended function.

The present invention overcomes the foregoing objections by associatingmeans with a condenser which localize the auxiliary steam supply toappreciably increase the deaeration qualities of the unit and furtherprovides an arrangement for returning condensate collected in thestorage hotwell through the localized area for removal of thenon-condensibles present therei Accordingly, it is an object of thisinvention to provide optimum removal of air and non-condensible gases inthe boiler feedwater of a power plant during all conditions of operationincluding startup and shutting down.

It is a further object to provide an improved condenser that isextremely compact and will accordingly be applicable in a systemconfronted with space limitations.

It is another object to overcome the objections present in prior typesystems and generally mentioned hereinabove.

According, with the foregoing in mind applicants provides means forremoving non-condensible gases includ- 3,151,461 Patented Dot. 6, 1964ing a recirculating means whereby feedwater collected in the storagehotwell is recirculated through a deaeratorlike arrangement and furtherprovides a steam source to said deaerator-like arrangement which acts toremove these non-condensible gases during startup and until such timethat the turbine is at normal operating pressures.

Other objects and advantages of the invention including the basic designand the nature of the improvements thereon will appear from thefollowing description taken in conjunction with the following drawings,in which:

FIGURE 1 is a front view of a condenser turbine system partly in sectionand showing the invention contemplated herein.

FIGURE 2 is a diagrammatic view of a modified arrangement of the systemshown in FIGURE 1.

Referring more particularly to FIGURE 1 of the drawings, there is showna condenser, generally designated 1, and comprising a shell including aplural set of condensing tubes 3 and 4 disposed in the upper portion ofthe shell.

As is well known a source of cooling water is passed through the tubesto condense the exhaust steam passed into the condenser from the turbine5 mounted in any convenient fashion thereon. The condensed feedwater iscollected in a collecting hotwell 6 formed beneath the condensing tubes.Collecting hotwell 6 is shown as comprising a substantially horizontaltank-like arrangement 7 having a U-shaped central portion 8.

Mounted to the U-shaped portion of the collecting hotwell is the meansfor removing non-condensib-le gases, generally designated 9, and shownby way of example as a deaerator. The deaerator as is well known isprovided with horizontal trays 2t) and a baffle or like arrangement 11for directing feedwater over the trays to break up the water in dropletsso that more complete removal of the air and non-condensible gases willtake place.

Removal of non-condensible gases from the feedwater in the means 9 isprovided by extracting steam from turbine 5 through line 10 which iscentrally disposed in the condenser and connected to the means forremoving non-condensible gases.

In this fashion condensed feedwater from the collecting hotwell 6 can bepassed therefrom into the means for removing non-condensible gases withthe provision of a transfer pump 19. Condensed water is passed fromhotwell 5 through line 12 which may include steam ejectors 21' or otherapplicable heat exchangers, to the deaerator 9.

Accordingly, deaerated feedwater will be collected in the storage means13 located at the bottom portion of the shell 2 and passed by condensatepump 14 to the boiler of the power plant.

As will be evident from the foregoing, and particularly during startup,it is possible to pass collected water from storage means 13 to theboiler through condensate pump 24. However, the feedwater collected inthe storage well would not be of the required degree of deaeration andaccordingly would tend to cause corrosion in the boiler and boiler feedsystem.

Since the turbine requires a certain run-in time before steam or" propertemperature and pressure can be provided through line 10 to thedeaerator, it is imperative that an alternative arrangement be fashionedto provide means for initially treating feedwater during the startup ofthe arrangement.

With the foregoing in mind applicants provide a recirculatingarrangement, generally designated 12, and shown as a bypass, line 5having valves 16' and 1.6" respectively disposed therein which passfeedwater in the hotwell 13 to the collecting means 6 or deaerator 9 inany convenient proportion. At the same time pump 19 can be started topass fluid in the collecting means 6 to the deaerator 9. Removal ofnon-condensible gases from the water passed through the deaerator 9 isaccomplished with the provision of a conduit 22' which is connected toan auxiliary steam supply and therefore permits the passage of the steamas desired through the storage means 13 up through the deaerator 9 toact on the water to provide the proper degree of deaeration.

Removal of the non-condensible gases is accomplished by theincorporation of a vent means 17 which discharges into the condensingportion of the condenser and with the provision of a valve 18 inextraction line 10 it will be evident that non-condensible gases andauxiliary steam are precluded from flowing into the turbine duringstartup and when the initial phase of deaeration is taking place.

As the usual venting arrangement will be associated with the maincondenser all of the attributes of a conventional vent condenser can betaken advantage of.

As will be evident to the skilled technician in this art, control of theinitial phase of deaeration can be conveniently tied into the controlroom of a power plant, or manually accomplished by simply closing downvalve 16' and/ or 16 and valve 16 as soon as indicators show thatturbine extraction pressure and temperature that is re quired fordeaeration has been reached. It is clear from FIGURE 1 thatrecirculation can be accomplished directly to the deaerator 9 by openingvalve 16' and closing valves 16 and 16".

The operation of the cycle shown and the manner in which it providestreated feedwater in accordance with the cycle illustrated in FIGURE 1will be evident to one skilled in the art from the foregoing descriptionand it is not believed that the operation thereof need be described infurther detail.

The form of the invention shown in FIGURE 2 diftors in some degree fromthe form shown in FIGURE 1 but the principles of construction and thegeneral principles of operation are similar. This form of the inventionincludes an additional condenser and is adapted to operate in accordancewith the principles contemplated herein with this additional condenser.

In this form of the invention plural condensers 21 and 22 are connectedby conduits 23 and 24 to the turbine exhaust.

Each condenser has a collecting hotwell Z and 26 arranged beneath thecondensing portion of the condenser to receive condensed steamtherefrom. As is evident from FIGURE 2 and in order to provide thecompact arrangement desired, the storage hotwell 27 is disposed in atrapezoidal-type tank which is spaced between the condensers 21 and 22and disposed beneath the turbine 28. The means for removingnon-condensible gases 29 is disposed in the upper portion of the shellof the storage hotwell 27. In this fashion water can be pumped bytransfer pumps 34) and 31 from the collecting hotwells to the means 29and passed therethrough in heat exchange relation with steam supplied tothe storage hotwell and flowing upwardly through the means 29 in orderto remove the air and non-condensible gases from "the feedwater. Thetreated feedwater can then be passed by condensate pump 31 tothe boilerof the power plant. During normal operation steam is supplied to themeans 29 from extraction line 32 which is substantially centrallydisposed in the above described arrangement.

In order to overcome the objections mentioned hereinabove duringstartup, an auxiliary steam source is provided for and steam therefromis passed to the storage hotwell 27 through conduit 33. In this fashionit will be evident that steam for passage in counterflow relation withfeedwater is provided when the temperature and pressure of the turbineexhaust is or has not yet reached required conditions. In similarfashion as was described in connection with FIGURE 1 feedwater collectedin storage hotwell 27 is passed to the collecting hotwells throughrecirculation means or bypass line 34 having valving 35' and 35 andclosing valves 35" and 35" conveniently disposed to preclude flow to theboiler and permit flow to the collecting hotwells or in any convenientproportion to deaerator 29 as desired by the operator. In this fashionwater collected in the storage well can be first treated by passing sameto the collecting hotwell and through the transfer pump to the means 29for deaeration before this feedwater is passed to the boiler.

If required, in operation fluid can be circulated directly to thedeaerator through lines 36 and 37 connected to lines 38 and 39 byclosing valves 35 and 35 and opening valves 35" and 35'.

Although this invention has been described with reference to specificcycles and apparatus, it will be appreciated that a wide variety ofchanges may be made within the ability of one skilled in the art withoutdeparting from the scope of this invention. For example, some of thecomponents of the apparatus may be reversed, certain features of theinvention may be used independently of others, and equivalents may besubstituted for the apparatus, all within the spirit and scope of theinvention as defined in the appended claims.

What is claimed is: i

I. A condenser including means for removing noncondensible gases fromboiler feedwater in a boiler feed system of a power plant including incombination, a turbine; said condenser having condensing means,collecting means, storage means, and means for removing non-condensiblegases arranged in how circuit relation so that exhaust from said turbineis passed through said condensing means, to said collecting means, andthrough said means for removing non-condensible gases before beingpassed to said storage means; pump means connected to said storage meansat one end and to the power plant at the other end to supply feedwaterthereto, an extraction line interconnecting said turbine and said meansfor removing non-condensible gases whereby steam flows from said turbineto said means for removing noncondensible gases to act on feedwaterpassing therethrough, recirculating means interconnecting said storageand collecting means and operative for a predetermined period of time toreturn feedwater from said storage means to said collecting means,conduit means connecting said means for removing non-condensible gasesto a source of steam whereby steam acts on the feedwater passing throughsaid means for removing non-condensible gases during startup of saidturbine to provide an initial source of deaerated feedwater for thepower plant, and means in the extraction line precluding flow into saidturbine during the startup period.

2. A condenser including means for removing non condensible gases fromboiler feedwater in a boiler feed system of a power plant including incombination, a turbine; said condenser having condensing means,collecting ieans, storage means, and means for removing non-condensiblegases arranged in flow circuit relation so that exhaust from saidturbine is passed through said condensing means, to said collectingmeans, and through said means for removing non-condensible gases beforebeing passed to said storage means; pump means connected to said storagemeans at one end and to the power plant at the other end to supplyfeedwater thereto, an extraction line interconnecting said turbine andsaid means for removing non-condensible gases whereby steam flows fromsaid turbine to said means for removing non-condensible gases to act onfeedwater passing therethrough; bypass means interconnecting said pumpmeans to said collecting means and operative for a predetermined periodof time to return fecdwater from said storage means to said collectingmeans, conduit means connecting said means for removing non-condensiblegases to a source of auxiliary steam whereby steam is passed to saidmeans for removing non-condensible gases to act on feedwater' passingtherethrough during startup of said turbine to provide an initial sourceof deaerated feedwater for the power plant, and valve means in theextraction line precluding flow into said turbine during the startupperiod.

3. A condenser including means for removing noncondensible gases fromboiler feedwater in a boiler feed system of a power plant including incombination, a turbine; said condenser having condensing means,collecting means, storage means, and means for removing noncondensiblegases, said means for removing non-condensible gases disposed betweensaid collecting means and said storage means to preclude flow from saidcollecting means to said storage means other than through said means forremoving non-condensible gases, a first pump means connected to saidcollecting means at one end and to said means for removingnon-condensible gases at the other end to pass feedwater from saidcollecting means through said means for removing non-condensible gases,a second pump means connected in said condenser and interconnecting saidstorage means to the power plant to supply feedwater thereto, anextraction line interconnecting said turbine and said means for removingnon-condensible gases whereby steam flow flows from said turbine to saidmeans for removing non-condensible gases to act on feedwater passingtherethrough, bypass means interconnecting said second pump means tosaid collecting means and operative for a predetermined period of timeto return feedwater from said storage means to said collecting means,conduit means connecting said means for removing non-condensible gasesto a source of auxiliary steam whereby steam is passed to said means forremoving non-condensible gases to act on the feedwater passingtherethrough for removing non-condensible gases from said feedwaterduring startup of said turbine to provide an initial source of deaeratedfeedwater for the power plant, and valve means in the extraction lineprecluding flow into said turbine during the startup period.

4. The combination claimed in claim 3 wherein said condensing means isdisposed at the top portion of the condenser, the storage means disposedat the bottom portion of the condenser, and the collecting meansdisposed between said condensing means and storage means and saidcollecting means including said means for removing noncondensible gases.

5. The combination claimed in claim 4 wherein the extraction line andsaid means for removing non-condensible gases are centrally disposed insaid condenser to coact in providing optimum removal of non-condensiblegases from the boiler feedwater.

6. The combination claimed in claim 3 wherein said condensing meanscomprises a first and second condenser each having a collecting meansarranged at the bottom portion thereof, each of said collecting meansincluding a pump means connected to said means for removingnoncondensible gases, and said storage means being disposed between thefirst and second condensing means and beneath the turbine.

7. The combination claimed in claim 6 wherein said eans for removingnon-condensible gases is centrally disposed in said combination to coactin providing optimum removal of non-condensible gases with theextraction line from said turbine.

8. A condenser including means for removing noncondensible gases fromboiler feedwater in a boiler feed system of a power plant including incombination, a turbine, said condenser comprising a shell having anupper portion and a lower portion, a condensing means comprising a nestof tubes arranged in the upper portion, a substantially horizontalcollecting means disposed beneath said condensing means and to collectsteam condensed by said tubes, a storage means disposed beneath saidcollecting means and at the bottom portion of said shell, said means forremoving non-condensible gases disposed centrally in said condenser andconnected to said collecting means, a transfer pump connected to saidcollecting means and said means for removing non-condensible gases topass feedwater of said collecting means to said means for removingnon-condensible gases, a condensate pump connected to said storage meansat one end and to said power plant at the other end to supply feedwaterthereto, and extraction line centrally disposed in said condenser andinterconnecting said turbine and said means for removing non-condensiblegases whereby steam flows from said turbine to said means for removingnon-condensible gases to act on feedwater passing therethrough, a bypassmeans interconnecting said condensate pump to said collecting means andoperative for a predetermined period of time to return feedwater fromsaid storage means to said collecting means, conduit means connectingsaid means for removing non-condensible gases to a source of auxiliarysteam whereby steam is passed to said means for removing non-condensiblegases to act on 'the feedwater passing therethrough during startup ofsaid turbine to provide an initial source of deaerated feedwater for thepower plant, and valve means in the extraction line precluding flow intosaid turbine during the startup period.

9. The combination claimed in claim 8 wherein said means for removingnon-condensible gases is centrally disposed in said condenser.

10. A first and second condenser includingmeans for removingnon-condensible gases from boiler feedwater in a boiler feed system of apower plant including in combination, a turbine, said turbine havingplural exhaust outlets, means for connecting said first and secondcondensers to said exhaust outlets of said turbine, each of thecondensers comprising a shell including a tube nest at the upper portionand a collecting means at the lower portion, storage means disposedbetween said first and second condensers, said means for removingnon-condensible gases connected to said storage means and at the upperportion thereof, a transfer pump means connected to each of saidcollecting means at one end and to said means for removingnon-condensible gases at the other end to pass feedwater from saidcollecting means to said means for removing non-condensible gases, atcondensate pump connected to said storage means at one end and to saidpower plant at the other end to pass feedwater thereto, an extractionline interconnecting said turbine and said means for removingnon-condensible gases whereby steam flows from said turbine to saidmeans for removing non-condensible gases to act on feedwater passingtherethrough, bypass means interconnecting said condensate pump to saidcollecting means and operative for a predetermined period of time toreturn feedwater from said storage means to said collecting means,conduit means connecting said means for removing non-condensible gasesto a source of auxiliary steam whereby steam is passed to said means forremoving non-condensible gases to act on feedwater passing there throughfor removing non-condensible gases during startup of said turbine toprovide an initial source of deaerated feedwater for the power plant,and valve means in the extraction line precluding flow into said turbineduring the startup period.

References Cited in the file of this patent UNITED STATES PATENTS1,353,855 Scanes Sept. 28, 1920 1,372,409 Ehrhart Mar. 22, 19211,628,737 Oliver May 17, 1927 1,962,183 Ehrhart June 12, 1934 2,542,873Karr Feb. 20, 1951 2,661,190 Kirkpatrick Dec. 1, 1953 2,663,547 Evans eta1. Dec. 22, 1953 2,848,197 Evans et al Aug. 19, 1958 2,916,260 Worn etal. Dec. 8, 1959 2,939,685 Worn et al. June 7, 1960 2,946,571 DroescherJuly 26, 1960

1. A CONDENSER INCLUDING MEANS FOR REMOVING NONCONDENSIBLE GASES FROMBOILER FEEDWATER IN A BOILER FEED SYSTEM OF A POWER PLANT INCLUDING INCOMBINATION, A TURBINE; SAID CONDENSER HAVING CONDENSING MEANS,COLLECTING MEANS, STORAGE MEANS, AND MEANS FOR REMOVING NON-CONDENSIBLEGASES ARRANGED IN FLOW CIRCUIT RELATION SO THAT EXHAUST FROM SAIDTURBINE IS PASSED THROUGH SAID CONDENSING MEANS, TO SAID COLLECTINGMEANS, AND THROUGH SAID MEANS FOR REMOVING A NON-CONDENSIBLE GASESBEFORE BEING PASSED TO SAID STORAGE MEANS; PUMP MEANS CONNECTED TO SAIDSTORAGE MEANS AT ONE END AND TO THE POWER PLANT AT THE OTHER END TOSUPPLY FEEDWATER THERETO, AN EXTRACTION LINE INTERCONNECTING SAIDTURBINE AND SAID MEANS FOR REMOVING NON-CONDENSIBLE GASES WHEREBY STEAMFLOWS FROM SAID TURBINE TO SAID MEANS FOR REMOVING NONCONDENSIBLE GASESTO ACT ON FEEDWATER PASSING THERETHROUGH, RECIRCULATING MEANSINTERCONNECTING SAID STORAGE AND COLLECTING MEANS AND OPERATIVE FOR APREDETERMINED PERIOD OF TIME TO RETURN FEEDWATER FROM SAID STORAGE